Sanya Mathura of Strategic Reliability Solutions Ltd
Dangerously high levels of water ingress noticed in one particular train (series of 6 GE Frame 5 Gas turbines).
Here's some background information: This particular facility produces liquefied natural gas and has 4 trains each consisting of 6 or 7 GE Frame 5 turbines. Each train was commissioned separately and are treated as separate units with differing dates for end of service life. For Train A, during a routinely scheduled oil change, the baseline results (after the new oil was filled in the sump) was determined to contain dangerously high levels of water (in excess of 2274ppm in one instance) for all of the individual sumps. Since this was a new charge of oil of 10,000 gallons the oil could not be discarded and replaced easily.
A vacuum dehydration unit was used to remove the excess levels of water. Since the entire train was down for maintenance, this was an opportune time to install the dehydration units in line with the sumps and have the oils circulated through the system to remove the water. Initially, samples were taken every 12 hours to monitor the levels of the water and every 24 hours to determine if any of the additives are being depleted and the presence of any wear metals or other contaminants.
After the first 12 hours of vacuum dehydration, one of the sumps experienced a 29% decrease of water (from 2274ppm to 1622ppm). Then, after 24 hours, this sump experienced a total of 94% decrease on water content (from the original value of 2274ppm to 138ppm) to a safe level. The dehydration system was removed from the sump after achieving the safe water content level and the water levels monitored for the next month. It was noticed that the levels did not return to the initial high levels that were firstly observed.
Upon further investigation, it was noted that the oil was stored in properly sealed flexibags however, the pumps used to siphon the oil into the sump were previously used for pumping water during the previous week. It was also noted that the hatch covers for the sumps remained open for cleaning work that was done on the inside of the sump in preparation for the new charge of oil. The hatches remained open for extended periods and the sump was not inspected before the new charge of oil was filled.